Method of making diaphragms



Dam. 1930. M. NYS-TROM 1,783,336

METHOD OF MAKING DIAPHRAGMS Original Filed July 2, 1926 wa s-W 12? 5/ WET/w A/XS'T/POM gripe/145;.

Patented Dec. 2, 1930 UNITED STATES PATENT OFFICE MARTIN NYSTROM, OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, TO

UNITED RESEARCH CORPORATION, OF LONG ISLAND CITY, NEW TORK, A CORPORA- TION OF DELAWARE METHOD OF MAKING DIA'PHRAGMS Application filed July 2, 1926, Serial No. 120,161.

My invention relates to diaphragms and it has a special relation to diaphragms for sound boxes of phonographs.

One object of the invention is to provide a one-piece diaphragm having a relatively thin and narrow hinge portion supporting a piston for vibration.

Another object of the invention is to provide a process of making a diaphragm by drawing a portion of a thinblank to make a hinge portion of reduced thickness.

Other objects and advantages will appear as the description proceeds.

Referring to the acompanying drawings:

Fig. 1 is a central sectional view of a sound box embodying my invention.

Fig. 2 is a central sectional view of a die, illustrating a step in the process of making the diaphragm embodied in the sound box shown in Fig. 1.

Figures 3 and 4 are central sectional views of blanks illustrating stages in the process of'making the diaphragm.

Fig. 5 is a side view of a completed diaphragm, and

Fig. 6 is a central sectional view of the completed diaphragm.

The diaphragm is extremely thin and comprises a central rigid portion or piston and an outer flexible portion or hinge 1 of reduced thickness. The hinge may be secured in a sound-box 2 by means of washer-s3.

In order that the piston may exercise a true piston action and not be flexed in operation, it may be deformed. The deformation may be in the shape of a cone 4, which may be slightly flattened at the apex for securement to a stylus bar 5.

Radial deformations 6 may be provided in the cone 4 to further insure rigidity. An annular deformation 7 having meeting truncoconical faces and surrounding the cone 4 Renewed March 12, 1930.

in the shape of annular corrugations 10 of any desired number.

The diaphragm may be made of a desired material, a light metal such as aluminum or aluminum alloy being especially advantageous, and latitude in the thickness and dimensions of the diaphragm is contemplated. An embodiment of the invention in which the diaphragm was made of aluminum and was approximately 00% in thickness throughout the piston area and approximately .002 in the hinge was found to be very satisfactory.

The low mass of diaphragms embodying the invention and the readily flexible character of the exterior portion or hinge makes possible a faithful reproduction of sound over a wide range of frequencies. The character of the diaphragm as being in one piece and lacking in joints renders it very durable.

In making the diaphragm a circular blank of a desired material, such, for instance, as aluminum or an aluminum alloy may be used, the blank being of a desired thickness as, for instance, .004. An outer marginal portion of the blank may be reduced to a desired thickness, as, for instance, .002.

The reduction in thickness is produced by subjecting the blank to a drawing action in a die 11 (Fig. 2) having an approximately cylindrical bore 12 therein by means of a plunger 13. The bore 12 may be tapered slightly to effect a continuous compression on the outer portion of the blank which is bent into a circular flange 14 and gradually reduced in thickness. After the blank is subjected to the drawing operation it may be ejected from the die by a plunger 15 moving thru the other end of the bore. The flange 14 may then be flattened out by successive operations in dies until the blank assumes the shape illustrated in Figure 3.

The central portion may then be shaped into a cone 4, and a deformation 7 by the action of suitable dies, as illustrated in Figure 4.

The radial deformations 6 and the corrugations 10 may then be impressed by suitable dies, the diaphragm taking the shape illustrated in Figures 5 and 6, but the invention is not limited to a precise sequence of steps in the formation of deformations and corrugations, except as indicated in the appended claims as these may be formed simultaneously or in any desired order.

The invention is not limited to the specific details of construction of the embodiment illustrated and described nor to the details of the process. For instance, the deformations may be greatly varied in shape and size. The diaphragm may be used not only in sound-boxes, but in loud-speakers, telephones and other devices in which it is desired to transmit or reproduce sound. A substantial range of equivalents is contemplated within scope of the appended claims.

I claim:

1. The process of making an acoustic diaphragm whichconsists in drawing the outer portion of an extremely thin metallic blank to reduce its thickness and deforming said outer portion to increase its flexibility.

2. The process cf making an acoustic diaphragm which consists in drawing the outer portion of a blank composed of aluminum and approximately .004" in thickness to reduce the thickness of the outer portion of sgid blank and thus render it extremely flexi le.

3. The process of making a diaphragm which consists in subjecting a blank to a drawing operation in an approximately cylindrical bore of a die, thus formin an approximately cylindrical flange, and t en flattening out said flange.

4. The process of making a diaphragm which consists in subjecting an extremely thin circular blank to a drawing operation in an approximately cylindrical bore of a die, thus forming a flange of reduced thick ness, and then flattening out said flan e.

5. The process of making a diap ragm which consists in drawing a circular blank in a bore of a die by means of a cylindrical plunger thus forming a flange of extreme thinness about a circular portion, and flattening out said flange and deforming said circular portion to render it rigid.

6. The process of makin an acoustic diaphragm which consists in rawing the outer portion of an extremely thin metallic blank to substantially reduce its thickness and drawing the central portion to produce a conical deformation therein without greatly reducing its thickness.

7. The process of making an acoustic diaphragm which consists in forming a conical deformation in the center of an extremely thin metallic blank and reducing the thickness of the portion 'of the blank surrounding said deformation so as to form a flexible hinge for the central portion.

8. The process of making an acoustic diaphragm which consists in drawing the outer portion of a blank composed of aluminum and approximately .004" in thickness to reduce the thickness of the outer portion of said blank and thus render it extremely flexible, further. deforming said outer portion to produce deformations therein and thereby increase its flexibility, and drawing said central portion into a conical shape to increase its rigidity without reducing its thickness.

9. The process of making an acoustic diaphragm which consists in drawing a blank in the cylindrical bore of a die by means of a cylindrical plunger, thus fori'ning between the surface of said plunger and the wall of said die a flange of extreme thinness about a relatively thick portion, and flattening out said flange between dies, further drawing the same to produce deformations therein and render it flexible, and drawing the central portion to produce a conical deformation therein and render it rigid.

MARTIN NYSTROM. 

